Between 1950 and 1970 the Department of Energy's Rocky Flats Plant generated contaminated waste, which was buried at the Idaho National Engineering Laboratory. This waste must now be retrieved and sent to a permanent disposal site. During retrieval the main contaminates to be controlled are compounds of plutonium and americium, and other volatile organic and inorganic substances. Since these substances are small sized, and extremely mobile, airborne concentrations must be kept to a minimum to effectively eliminate personnel uptake during retrieval operations. This invention relates to a drill string enclosure which is required to prevent release of contaminates and allows maximum visibility for the workers during drilling and sampling of hazardous waste sites. The drill string enclosure consists of six component parts a top bracket, an upper acrylic cylinder, an acrylic drill casing guide, a lower acrylic cylinder, a bottom bracket, and three flexible ducts.
Prior to the development of the drill string enclosure, the primary means for the control of airborne contaminate particles of plutonium and americium was the control of the moisture content of the soil in and around the dig site. The addition of moisture to the surface soil of a dig is a well known method of dust control used by many industries. However, effective monitoring and control of the airborne particles by moisture addition alone cannot, as a sole means of containment, meet the stringent requirements imposed by the federal and state governments for hazardous waste sites. Additionally, coverings and air locks which reduce the amounts of contaminates released are more costly and hinder the visibility of the workers during drilling operations. The present invention presents a novel enclosure which allows for maximum visibility of the drill site with a minimum release of contaminates into the atmosphere.